"The right of trial by jury shall be inviolate, except that, in civil cases, laws may be passed to authorize the rendering of a verdict by the concurrence of not less than three-fourths of the jury." -- Ohio Constitution
"The right of trial by jury shall remain, but shall be waived in all civil cases unless demanded by one of the parties in the manner prescribed by law." -- Michigan Constitution
"Trial by jury is an inviolate right and shall be secured to all, but in a civil cause three-fourths of the jury may render a
verdict." -- California Constitution
"The right of trial by jury shall remain inviolate; but the Legislature may authorize the trial of civil causes by a jury of six persons." -- New Jersey Constitution
"The right of trial by jury shall remain inviolate, and shall extend to all cases at law without regard to the amount in controversy; but a jury trial may be waived by the parties in all cases in the manner prescribed by law. Provided, however, that the legislature may, from time to time, by statute provide that a valid verdict, in civil cases, may be based on the votes of a specified number of the jury, not less than five-sixths thereof." -- Wisconsin Constitution
(Sources: State websites.)
And see more quotes from state constitutions in Part I, posted June 29.